Crystalline ZSM-5, and its conventional preparation using tetrapropylammonium cations as a structure directing agent, are taught by U.S. Pat. No. 3,702,886 and U.S. Pat. No. Re. 29,948, the entire disclosures of which are incorporated herein by reference. Conventional ZSM-5 has a distinctive X-ray diffraction pattern which distinguishes it from organic conversion reactions.
In addition to tetrapropylammonium cations, a large number of other organic nitrogen compounds, including certain diquaternary ammonium compounds, have been shown to direct the synthesis of ZSM-5. For example, U.S. Pat. No. 4,585,638 discloses that the synthesis of ZSM-5 can be directed by the diquaternary cation (alkyl)3N+(CH2)6N+(alkyl)3, where the alkyl group is propyl or butyl.
According to the present invention, it has now been found that ZSM-5 can be synthesized using certain novel bis(N-pentylpyrrolidinium)-diquat-n cations, where n=4, 5 or 6, as a structure directing agent. The ZSM-5 can be made across a wide range of Si/Al ratios (infinity to 12) and, in some cases, it has been found that novel ultra-small forms of ZSM-5 can be produced.